Investigating the X-ray polarization of lamp-post coronae in BHXRB

TL;DR

This study uses general relativistic Monte Carlo simulations to predict X-ray polarization signatures from lamp-post coronae in black hole X-ray binaries, aiming to aid future polarimetric observations in constraining black hole and accretion flow properties.

Contribution

It provides the first detailed predictions of X-ray polarization from lamp-post coronae considering relativistic effects, highlighting dependencies on black hole spin and corona geometry.

Findings

Polarization degree depends on black hole spin and corona height.

Relativistic effects significantly influence polarization signatures.

Predictions will guide interpretation of upcoming X-ray polarimetric data.

Abstract

High-sensitivity X-ray polarimetric observations of black hole X-ray binaries, which will soon become available with the launches of space-borne X-ray observatories with sensitive X-ray polarimeters, will be able to put independent constraints on the black hole as well as the accretion flow, and possibly break degeneracies that cannot be resolved by spectral/timing observations alone. In this work we perform a series of general relativistic Monte-Carlo radiative transfer simulations to study the expected polarization properties of X-ray radiation emerging from lamp-post coronae in black hole X-ray binaries. We find that the polarization degree of the coronal emission of black hole X-ray binaries is sensitive to the spin of the black hole, the height of the corona, and the dynamics of the corona.